Apparatus and method for separating particles from a cyclonic fluid flow

ABSTRACT

An anti-reentrainment device is provided for use with a cyclone separator. The anti-reentrainment device has a plurality of vane upwardly extending members positioned in the bottom of a cyclone chamber and extending radially inwardly across the bottom. The vanes separate the bottom of the cyclone from the cyclonic fluid flow portion, thereby creating a reduced flow region above deposited particles settling on the bottom of the cyclone. The device impedes the cyclonic flow from reentraining the deposited particles.

FIELD OF THE INVENTION

The present invention relates generally to cyclonic separators. In oneparticular application, the invention relates to the cyclonic separationof particulate material from an air flow.

BACKGROUND OF THE INVENTION

The use of a cyclone, or multiple cyclones connected in parallel orseries, has long been known to be advantageous in the separation ofparticulate matter from a fluid stream. Typically, a relatively highspeed fluid stream is introduced tangentially to a generally cylindricalor frusto-conical container, wherein the dirty air stream is acceleratedaround the inner periphery of the container. The centrifugalacceleration caused by the travel of the fluid in a cyclonic streamthrough the cyclone causes the particulate matter to be disentrainedfrom the fluid flow and, eg., to collect at the bottom of the container.A fluid outlet is provided for the extraction of the fluid from thecentre of the top of the cyclone container, as is well known in the art.

A typical flow path in a cyclone separator is as follows. Fluid to betreated is introduced tangentially at a fluid inlet located at an upperend of the cyclone container. The fluid stream rotates around the innersurface of the cyclone container, and spirals generally downwardlyaround the inner surface of the container (if the cyclone container isvertically disposed). At a bottom end of the cyclone container the fluidstream travels radially inwardly, generally along the bottom of thecontainer and then turns upwardly and proceeds vertically up and out ofthe cyclone container. The particulate matter separating action of thecyclonic flow occurs substantially around the inner surface of thecontainer. Once the fluid moves inwardly to the centre of the container,and upwardly there through, there is little or no dirt separationachieved.

The difficulty experienced with prior art cyclonic separators is thereentrainment of the deposited particles back into the outgoing fluidflow. Deposited particles exposed to a high speed cyclonic flowthereover have a tendency to be reentrained. This is particularlyproblematic when the container has a solid bottom portion in which thedirt collects. However, there is a potential reentrainment problem evenif the bottom of the container has a passageway provided in the bottomthereof to convey the separated particulate material away from thecontainer.

If a high degree of separation is required, it is known to connect aplurality of cyclones in series. While using several cyclones in seriescan provide the required separation efficiency, it has several problems.First, if the separators are to be used in industry, they generally needto accommodate a high flow rate (eg. if they are to be used to treatflue gas). The use of a plurality of cyclones increases the capital costand the time required to manufacture and install the separators.Further, the use of a plurality of cyclones increases the spacerequirements to house the cyclones. Accordingly, there is a need for animproved anti-reentrainment means for cyclonic separators.

SUMMARY OF THE INVENTION

In has now been discovered that a single cyclone having improvedefficiency (eg. up to 99% efficiency) may be manufactured by positioningin the cyclone chamber a member for creating a dead air space below thecyclonic flow region of the cyclone chamber. This construction trapsseparated material below the cyclonic flow region and inhibits thereentrainment of the separated material. Thus, a single cyclone may beused in place of a plurality of cyclones to achieve the same separationefficiency.

In accordance with the instant invention, there is provided a separatorfor separating entrained particles from a fluid flow, the separatorcomprising a cyclone chamber having a cyclonic flow region and a bottom,the cyclonic flow region having a centre, a longitudinal axis, an outerperipheral portion, an inner portion and a radial width, a fluid inletfor introducing a cyclonic fluid flow to the cyclonic flow region, afluid outlet for removing the fluid flow from the cyclone chamber, aplurality of vanes positioned adjacent the bottom and extending inwardlytowards the centre, the vanes having an inner portion and an outerportion, and a cover member spaced from the bottom and positioned abovethe vanes.

In one embodiment, the cover member is positioned over the inner portionof the vanes. The cover member may have a radial width that is from25-75% and preferably from 25-35% of the radial length of the vanes.

In another embodiment, the vanes extend downwardly from the covermember. The vanes may have a height of at least three-quarters thedistance between the bottom and the cover member. Preferably, all of thevanes are of substantially the same height. Further, preferably thevanes are substantially parallel to the longitudinal axis.

In another embodiment, the vanes extend upwardly at an angle of up to45° to the longitudinal axis.

In another embodiment, the vanes are equidistantly spaced around thebottom.

In another embodiment, the vanes extend to the centre and the covermember has a radial width that is from 25-35% of the radial width of thecyclonic flow region.

In another embodiment, the vanes curve in the downstream direction asthey extend inwardly from the outer periphery.

In another embodiment, the vanes extend radially inwardly from the outerperiphery.

In another embodiment, the separator further comprises a cleaner headadapted for movement over a floor and having a fluid nozzle positionableadjacent the floor, the nozzle in fluid flow communication via apassageway with the separator fluid inlet, a handle for moving thecleaner head over the floor, and a casing for housing the cyclonechamber. The separator may further comprise a centre feed pipe, thevanes extend to the centre feed pipe and the cover member extendsoutwardly from the centre feed pipe, the cover member having a radialwidth that is from 25-75% of the radial length of the vanes.

In accordance with the instant invention, there is also provided aseparator for separating entrained particles from a fluid flow, theseparator comprising a cyclone chamber having a cyclonic flow region,the cyclonic flow region having a centre, a longitudinal axis, an outerperipheral portion, an inner portion and a radial width, means forintroducing a fluid flow to the cyclone flow region for cyclonicrotation therein, means for removing the fluid flow from the cyclonechamber, particle receiving means disposed beneath the cyclonic flowregion for receiving particles separated from the fluid flow,separations means for creating non-rotational flow regions positionedbeneath the cyclonic flow region and which are have an open to forcommunication with the cyclonic flow region.

In another embodiment, the cyclone chamber has a bottom and comprises asealed chamber except for the means for introducing the fluid flow andthe means for removing the fluid flow and the separation means ispositioned at the bottom of the cyclone chamber.

In another embodiment, the separation means comprises cover meanspositioned in the inner portion of the cyclonic flow region and bafflemeans extending in the direction of the longitudinal axis of thecyclonic flow region.

In another embodiment, the separator is incorporated into a vacuumcleaner having a cleaner head and casing in which the cyclone separatoris positioned, the cyclone chamber having centre feed means, the bafflemeans extends inwardly to the centre feed means and the cover meansextends outwardly from the centre feed means, the cover means having aradial width that is from 25-75% of the radial length of the bafflemeans.

In another embodiment, the separator is incorporated into a vacuumcleaner having a cleaner head and casing in which the cyclone separatoris positioned, the baffle means extends inwardly to the centre and thecover means extends outwardly from the centre, the cover means having aradial width that is from 25-75% of the radial length of the bafflemeans.

In accordance with the instant invention, there is also provided amethod for separating entrained particles from a fluid flow, the methodcomprising the steps of introducing a fluid to flow cyclonically in achamber having a cyclonic flow region, the cyclonic flow region havingan inner portion and an outer portion, removing particles from the fluidflow in the cyclone chamber and retaining the separated particles in aplurality of areas provided beneath the outer portion of the cyclonicflow region, each of the areas having an upper portion which is open tobe in flow communication with the cyclonic flow region, and removing thefluid flow from the chamber.

In one embodiment, the method further comprises the step of using bafflemeans having an outer portion and an inner portion to retain theseparated particles in the areas.

In another embodiment, the method further comprises the step of using acap member positioned above the inner portion of the baffle means toreduce the reentrainment of separated particles.

In another embodiment, the method further comprises the dirt separationmechanism for a vacuum cleaner and the method further comprises passinga cleaning head over a surface to clean the surface.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention, and to show moreclearly how it may be carried into effect, reference will now be made byway of example to the accompanying drawings of a preferred embodiment ofthe present invention, in which:

FIG. 1 is an isometric view of a cyclone separator according to thepresent invention;

FIG. 2 is a cross-section along the line 2—2 of the cyclone chamber ofFIG. 1;

FIG. 3 is a cross-section along the line 2—2 of an alternate embodimentof the cyclone chamber of FIG. 1;

FIG. 4 is an isometric view of a household vacuum cleaner incorporatinga cyclone separator according to the present invention; and,

FIG. 5 is an enlarged isometric view of the removable bin of the vacuumcleaner of FIG. 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The improvements in cyclonic separators described herein may be usedwith or in place of cyclonic separation devices of any sort which areused to separate particulate material from a fluid stream. For example,they may be used with a fluid stream consisting of one or more gassessuch as industrial dust collection systems (eg. flue gas scrubbing),they may be used to classify particles according to their size or theymay be used with a fluid stream consisting of one or more liquids (eg. ahydrocyclone) or with fluid streams comprising a gas/liquid mixture. Itwill be appreciated that they these cyclone separators may be used inany manner known in the particle separation art.

A cyclone separator 30 according to the present invention is shown inFIG. 1. In this embodiment, separator 30 has a bin 32 having a fluidinlet 34 for introducing a cyclonic fluid flow to bin 32, a bottom 36,an exterior wall 38 and a fluid outlet 40. Bin 32 thus defines a cyclonechamber 42. Inlet 34 is any inlet capable of introducing a cyclonic flowto bin 32, and may be tangentially disposed to bin, or may be an axialor screw inlet, or other type. It will be appreciated that cyclonechamber 42 may be of any design known in the art. For example inlet 34and outlet 40 may be positioned at any location and the wall 38 ofchamber 42 may be of any construction known in the art.

Disposed above bottom 36 are a plurality of upwardly extending membersor vanes 50 extending radially outwardly over bottom 36. Vanes 50 havespaced apart opposed surfaces 60 and are preferably thin members. A cap52 is disposed above an upper edge 54 of vanes 50 in the central portionof bin 32. Cap 52 has a perimeter 56 and an upper surface 58. As shownin FIG. 2, vanes 50 extend from a position under cap 52 to wall 38. Asshown in FIG. 1, cap 52 has a flat upper surface 58. However, it will beappreciated that upper surface 58 may be of any particular profile.

Vanes 50 may extend substantially radially as shown in FIG. 2 or theymay be curved as shown in FIG. 1. Preferably, the vanes are planar (i.e.they extend in a straight plane). If the vanes are curved, then thevanes are preferably curved in the upstream direction, relative to thedirection of cyclonic flow (as shown in FIG. 1).

Referring again to FIG. 1, in use, fluid (which may be a liquid or a gasbut is preferably a gas) is introduced via inlet 34 to flow cyclonicallyin bin 32. As the cyclonic flow travels downwardly in bin 32, particlesentrained in the fluid flow are separated therefrom and fall to bottom36 more or less along wall 38. As the cyclonic fluid flow reaches thelower portion of bin 32, the downward direction of the flow is reversedand fluid moves inwardly and upwardly, in a cyclonic manner, to outlet40.

Vanes 50 are separation means that create a “dead” space immediatelyabove bottom 36 by substantially preventing cyclonic fluid flow betweenadjacent vanes 50. These dead spaces are regions of non-rotational flowwherein the portion of these regions that are not beneath cap 52 have anopen top. The vanes act as vertically extending baffles to produce deadspaces that encourage the deposition of separated particles on bottom 36and at least partially separates the deposited particles from thecyclonic fluid flow to impede reentrainment of the deposited particles.Some radially inward fluid flow is experienced between adjacent vanes50, however.

Preferably vanes 50 extend under cap 52 to reduce or inhibit thereentrainment of deposited particles (see the portion of vanes 50 instippled lines in FIGS. 2 and 3). The portion of vanes 50 which extendunder cap 52 comprise the inner portion of vanes 50 and they may beprovided below the inner portion of cyclone chamber 42. The portion ofthe vanes 50 which cap 52 does not overlie are the outer portion ofvanes 50 and they are provided below the outer or peripheral portion ofcyclone chamber 42. In operation, as the radial inward fluid flow movestoward the centre of bin 32, it may reentrain some of the depositedparticles. Near the centre of bin 32, the inward flow moves upwardlytowards outlet 40. To impede the inward flow from retaining itsentrained particles, cap 52 is provided to interfere with a smoothupward turn in fluid flow, which interference causes the upward fluidflow to shed at least a portion of the reentrained particles. Suchparticles fall under the influence of gravity back to bottom 36.

While the vanes 50 may end at perimeter 56 of cap 52, preferably, cap 52extends over a significant portion of the radial length of vanes 50,more preferably about 25-75% and, most preferably, about 25-35% of thelength of vanes 50 to prevent reentrainment. Thus the size of cap 52compared to the surface area of bottom 36 may vary substantially (seefor example FIGS. 2 and 3). In particular, if vanes 50 extend all theway to the centre of bin 32 (eg. as shown in FIG. 2), then cap 52 mayhave a radial width W_(c) which is about 25-75% and, more preferably,about 25-35% of the radial width of bin 32 W _(b). However, if vanes 50do not extend all the way to the centre of bin 32 (as shown in FIG. 3),then cap 52 may have a radial width which so as to cover about 25-75%and, more preferably, about 25-35% of the radial length Wv of vanes 50.If vanes 50 do not extend all the way to the centre of bin 32, it willbe appreciated that cap 52 does not have to extend all the way to thecentre of bin 32. This may occur if the cyclonic flow region in bin 32defines an annular space as opposed to a cylindrical space.

The height H of vanes 50 in the direction of the longitudinal axis A ofbin 32 may be varied depending upon the size of the particles to beseparated from the fluid stream, the properties of the fluid and amountof particles to be collected between emptying cycles. As particles aredeposited on bottom 36, the effective depth of vanes 50 is decreasedbecause the increased depth of settled particles on bottom 36 buries aportion of vanes 50. The height of vanes 50 is preferably chosen suchthat the maximum depth of particles to be collected between emptyingcycles is about three-quarters of the vane height. The vertical heightof vanes 50 may vary along their length, although a constant height vaneis preferred. If the height of vanes 50 varies, then vanes 50 preferablyhave an increased height adjacent cap 52 than at wall 38 (as is shown inFIG. 1).

Vanes 50 may extend upwardly at an angle of up to about 45° to thecyclonic axis A (i.e the angle between the bottom of opposed surface 60and axis A may be up to about 45°). Preferably, vanes 50 extendperpendicularly upwardly from bottom 36, and preferably extend generallyparallel to the cyclonic axis A of the cyclonic fluid flow in bin 32.

Vanes 50 may extend in the space between bottom 36 and the lower surfaceof cap 52. Preferably, vanes 50 preferably have a height equal to aboutthree-quarters of the vertical distance V between cap 52 and bottom 36.Preferably vanes 50 extend downwardly from cap 52 towards bottom 36 (inwhich case there may be a gap between the bottom of vanes 50 and bottom36 which has a height equal to about one-quarter of the verticaldistance V between cap 52 and bottom 36) and they may extend to contactbottom 36 (eg. see FIG. 1). If cap 52 is positioned farther from vanes50, the beneficial anti-reentrainment properties of the presentinvention are reduced.

In the one application as exemplified in FIGS. 4 and 5, cycloneseparator may be used as the cyclone separator for a vacuum cleaner.While separator 30 may be used in any vacuum cleaner (eg. upright,canister or a central vacuum cleaning system), it will be described asit may be used in an upright vacuum cleaner.

In this application, separator 30 according to the present invention isincorporated into a domestic upright vacuum cleaner, indicated generallyat 200. Vacuum cleaner 200 has a floor cleaning head 202, having glidemeans (eg. wheels 204) for moving the cleaner head across a floor, amain casing 206 rotatably attached to cleaner head 202, and a handle 208for moving cleaner 200 across the floor. Main casing 206 housesseparator 30. In this embodiment, separator 30 comprises a central airfeed conduit 210 in communication with a air nozzle (not shown) adjacentthe floor in cleaner head 202, and leading to a curved air inlet 34.

Bin may be removable mounted in main casing 206 by any means known inthe art. For example, referring to FIG. 5, bin 32 may be removable frommain casing 206 via the application of finger pressure to a handle 212.Bin 32 has an open end 214 and defines a cyclone chamber 42. Bottom 36has a plurality of vanes 50 extending thereacross. An air outlet isdisposed centrally in an upper portion of cyclone chamber 42.

In use, an air flow created by a motor (not shown) is created in vacuumcleaner 200 drawing air from the nozzle of cleaner head 202, throughcentre air feed conduit 210 and introduced to cyclone chamber 42 viainlet 34. Cyclonic flow is maintained in cyclone chamber 42 therebycausing particles entrained in the cyclonic flow to be deposited onbottom 36. Vanes 50 act to separate the cyclonic air flow from bottom36, thus impeding reentrainment, as described above. Air then exitscyclone chamber via air outlet 40, though the motor and then exits thecleaner.

After operation of vacuum cleaner 200, particles of varying size collecton bottom 36 in bin 32. To empty such collected contents, bin 32 isremoved from main casing 206, such as via handle 212, and inverted(typically over a refuse collector of the like) to cause the collectedparticles on bottom 36 to fall from bin 32 under the influence ofgravity. Bin 32 is then returned to its upright position and reinstalledin cleaner 200, in preparation of further use.

Accordingly, the vane members according to the present invention providebeneficial particle separation characteristics in a cyclone separator.The vane members provide for a physical separation between the depositedparticles in the bottom of the cyclone and the cyclonic flow above thevane members, thereby beneficially reducing the reentrainment ofdeposited particles into these fluid flow. Performance of the cycloneseparator is thereby enhanced.

While the above description constitutes the preferred embodiments, itwill be appreciated that the present invention is susceptible tomodification and change without departing from the fair meaning of theproper scope of the accompanying claims.

We claim:
 1. A separator for separating entrained particles from a fluidflow, the separator comprising: a) a cyclone chamber having a cyclonicflow region and a closed bottom, the cyclonic flow region having acenter, a longitudinal axis, an outer peripheral portion, an innerportion and a radial width; b) a fluid inlet for introducing a cyclonicfluid flow to the cyclonic flow region; c) a fluid outlet for removingthe fluid flow from the cyclone flow region; d) a plurality of vanespositioned adjacent the bottom and extending inwardly towards thecenter, the vanes having an inner portion and an outer portion andcreating a dead space immediately above the bottom; and, e) a covermember spaced from the bottom and positioned above the vanes.
 2. Theseparator of claim 1 wherein the cover member is positioned over theinner portion of the vanes.
 3. The separator of claim 1 wherein thecover member has a radial width that is from 25-75% of the radial lengthof the vanes.
 4. The separator of claim 1 wherein the cover member has aradial width that is from 25-35% of the radial length of the vanes. 5.The separator of claim 3 wherein the vanes extend downwardly from thecover member.
 6. The separator of claim 5 wherein the vanes have aheight of at least three-quarters the distance between the bottom andthe cover member.
 7. The separator of claim 1 wherein all of the vanesare of substantially the same height.
 8. The separator of claim 1wherein the vanes are substantially parallel to the longitudinal axis.9. The separator of claim 1 wherein the vanes extend upwardly at anangle of up to 45° to the longitudinal axis.
 10. The separator of claim1 wherein the vanes are equidistantly spaced around the bottom.
 11. Theseparator of claim 1 wherein the vanes extend to the center and thecover member has a radial width that is from 25-35% of the radial widthof the cyclonic flow region.
 12. The separator of claim 1 wherein thevanes curve in the downstream direction as they extend inwardly from theouter periphery.
 13. The separator of claim 1 wherein the vanes extendradially inwardly from the outer periphery.
 14. The separator of claim 1further comprising: (a) a cleaner head adapted for movement over a floorand having a fluid nozzle positionable adjacent the floor, the nozzle influid flow communication via a passageway with the separator fluidinlet; (b) a handle for moving the cleaner head over the floor; and, (c)a casing for housing the cyclone chamber.
 15. The separator of claim 14further comprising a center feed pipe, the vanes extend to the centerfeed pipe and the cover member extends outwardly from the center feedpipe, the cover member having a radial width that is from 25-75% of theradial length of the vanes.
 16. A separator for separating entrainedparticles from a fluid flow, the separator comprising: a) a cyclonechamber having a cyclonic flow region, the cyclonic flow region having acenter, a longitudinal axis, an outer peripheral portion, an innerportion and a radial width; b) means for introducing a fluid flow to thecyclone flow region for cyclonic rotation therein; c) means for removingthe fluid flow from the cyclonic flow region; d) particles receivingmeans disposed beneath the cyclonic flow region for receiving particlesseparated from the fluid flow and having a sealed bottom; e) separationmeans for creating non-rotational flow regions positioned beneath thecyclonic flow region and which are open to communication with thecyclonic flow region.
 17. The separator of claim 16 wherein the cyclonechamber has a bottom and comprises a sealed chamber except for the meansfor introducing the fluid flow and the means for removing the fluid flowand the separation means is positioned at the bottom of the cyclonechamber.
 18. The separator of claim 16 wherein the separation meanscomprises cover means positioned in the inner portion of the cyclonicflow region and baffle means extending in the direction of thelongitudinal axis of the cyclonic flow region.
 19. The separator ofclaim 18 wherein the cover means has a radial width that is from 25-75%of the radial length of the baffle means.
 20. The separator of claim 18wherein the cover means has a radial width that is from 25-35% of theradial length of the baffle means.
 21. The separator of claim 19 whereinthe baffle means extend downwardly from the cover member.
 22. Theseparator of claim 20 wherein the baffle means have a height of at leastthree-quarters the distance between the bottom and the cover means. 23.The separator of claim 18 wherein the baffle means are substantiallyparallel to the longitudinal axis.
 24. The separator of claim 18 whereinthe baffle means extend upwardly at an angle of up to 45° to thelongitudinal axis.
 25. The separator of claim 18 wherein the separatoris incorporated into a vacuum cleaner having a cleaner head and casingin which the cyclone separator is positioned, the cyclone chamber havingcenter feed means, the baffle means extends inwardly to the center feedmeans and the cover means extends outwardly from the center feed means,the cover means having a radial width that is from 25-75% of the radiallength of the baffle means.
 26. The separator of claim 18 wherein theseparator is incorporated into a vacuum cleaner having a cleaner headand casing in which the cyclone separator is positioned, the bafflemeans extends inwardly to the center and the cover means extendsoutwardly from the center, the cover means having a radial width that isfrom 25-75% of the radial length of the baffle means.
 27. A method forseparating entrained particles from a fluid flow, the method comprisingthe steps of: (a) introducing a fluid to flow cyclonically in a chamberhaving a cyclonic flow region, the cyclonic flow region having an innerportion and an outer portion; (b) removing particles from the fluid flowin the cyclone chamber and retaining the separated particles in aplurality of areas provided beneath the outer portion of the cyclonicflow region, each of the areas having an upper portion which is open tobe in flow communication with the cyclonic flow region; and, (c)removing the fluid flow from the chamber.
 28. The method as claimed inclaim 27 further comprising the step of using baffle means having anouter portion and an inner portion to retain the separated particles inthe areas.
 29. The method as claimed in claim 28 further comprising thestep of using a cap member positioned above the inner portion of thebaffle means to reduce the reentrainment of separated particles.
 30. Themethod of claim 27 wherein the separator comprises the dirt separationmechanism for a vacuum cleaner and the method further comprises passinga cleaning head over a surface to clean the surface.